In recent years, Organic Light-Emitting Diode (OLED) displays have become very popular emerging flat panel displays both at home and abroad. This is because OLED displays are self-luminous, wide viewing angle, short reaction time, high luminous efficiency, wide color gamut, low operating voltage, thin thickness, can produce large size and flexible display and simple process characteristics, and it also has the potential of low cost.
In OLED displays, thin film transistors (TFTs) are often used in conjunction with capacitor storage signals to control the luminance gray scale of an OLED. In order to achieve the purpose of constant current drive, each pixel needs at least two TFT and a storage capacitor to form, that is, 2T1C mode. FIG. 1 is a circuit diagram of a pixel of a conventional OLED display. Referring to FIG. 1, a pixel of an existing OLED display includes two thin film transistors (TFTs) and a capacitor, and specifically includes a switching TFT T1, a driving TFT T2, and a storage capacitor Cs. The driving current of the OLED is controlled by the driving TFT T2, the current size is: IOLED=k(Vgs−Vth)2, where k is the intrinsic conduction factor of the driving TFT T2, which is determined by the characteristics of the driving TFT T2 itself, Vth is the threshold voltage of the driving TFT T2, and Vgs is the voltage between the gate and the source of the driving TFT T2. Due to long-term operation, the threshold voltage Vth of the driving TFT T2 may drift, thereby causing the driving current of the OLED to change, so that the display of the OLED display may be poor, and the quality of the display may be affected.